Gold coated magnetic beads are obtained using a proprietary procedure. The particles show excellent chemical stability, magnetic properties and an intense surface plasmon resonance in the visible-NIR region (Figure 2).

AAAAAAAAAAAAAAAAAFigure 2. UV-vis absorption of the MaGOLD 500 beads

The average particle size is about 2-3 µm for the MaGOLD 2.5 and 500 nm for the MaGOLD 500 with a narrow size distribution. Nanoparticles can be conjugated with thiol-terminated polyethylene glycol containing di­fferent terminal functional groups, including amine, carboxyl, azido and biotin (Figure 3). Other sizes are available as a custom request.

MaGOLD are the first beads on the market based on gold-coated strategy for biological separation. The main advantages of the MaGOLD technology with respect to the other commercial magnetic beads are:

1) Fast separation time
2) High chemical stability, inertness and biocompatibility;
3) Possibility to tune the density of functional groups on the surface;
4) Possibility to have different functional groups on the same nanoparticle.